Every list ages. People change jobs, abandon mailboxes, lose interest or simply stop reading. Carrying on writing to everyone, indefinitely, seems harmless: after all, an unread message costs almost nothing. In reality it costs reputation. Providers watch how their users react to your messages, and a growing share of recipients who ignore everything lowers trust in the whole send, including the messages meant for people who do read.
Defining «inactive»
The first problem is deciding who is truly inactive. For years the reference metric was the open, measured with an invisible image in the message. Today it is far less reliable: some clients download images automatically to protect privacy, generating opens nobody made, while others block images and hide real opens.
That is why it pays to combine several signals:
- clicks on a link, much more reliable than opens;
- activity outside email: account logins, purchases, visits tracked after a click;
- replies to messages;
- opens, but only as a hint, separating automatically generated ones where possible;
- sign-up date, so that someone who joined a few weeks ago isn't treated as inactive.
A practical definition might be: no clicks and no activity on the site or account in the last six months, for someone subscribed for at least six months. The window should be adapted to sending frequency: with a monthly newsletter six months means six messages, with daily sends it means hundreds.
Segmenting by engagement level
Rather than a hard split between active and inactive, it is more useful to work in bands.
| Band | Indicative definition | Treatment |
|---|---|---|
| active | click or activity in the last 90 days | regular sends |
| lukewarm | last activity 3 to 6 months ago | reduced frequency, better content |
| inactive | no activity for 6 to 12 months | re-engagement campaign |
| lost | over 12 months, no response to re-engagement | suspension |
The lukewarm band is where a lot can still be recovered, often just by lowering frequency or sending the kind of content that generated the most clicks in the past.
The re-engagement campaign
Before suspending a contact, it is worth asking them explicitly whether they want to stay. A good re-engagement campaign is short and honest:
- a first message reminding them what the list offers and asking them to confirm their interest with a click;
- a second message, one or two weeks later, for those who didn't respond, perhaps with particularly useful content;
- a final message clearly announcing that sending will stop, with a link to stay.
Anyone who clicks moves back to active. Anyone who responds to none of the three messages is suspended. The subject line should be explicit, with no tricks: «Do you want to keep receiving our updates?» works better than an ambiguous subject that only tries to squeeze out an open.
It is important to send re-engagement in modest volumes rather than all at once: by definition it goes to a poorly engaged audience, so its metrics are weaker. If the inactive band is very large, split it over several days.
The sunset policy
A sunset policy is the written rule that decides when a contact stops receiving messages for lack of engagement. Having it in writing, and applying it automatically, avoids two opposite mistakes: never cleaning for fear of losing numbers, or carrying out sudden, drastic purges every now and then.
A good sunset policy defines:
- the inactivity window, tied to sending frequency;
- exceptions, for example customers with an active contract who must still receive service communications;
- the re-engagement sequence that precedes suspension;
- what happens to a suspended contact: it stays in the database, excluded from promotional sends, or it is deleted according to the planned retention periods.
Bear in mind that suspension concerns promotional messages. Transactional emails, such as a receipt or a security alert, follow the user's actions and do not depend on their engagement with the newsletter.
The fear of losing subscribers
Shrinking the list feels like a loss, but subscriber count is not an outcome in itself. What matters is how many people get the message in their inbox and act on it. Often, after a well-run clean-up, the absolute number of clicks stays similar or goes up, because messages meant for active readers stop landing in spam.
In short
- Subscribers who ignore everything lower the reputation of the whole send.
- Opens are not enough: clicks and on-site activity are more reliable signals.
- Working in engagement bands lets you recover lukewarm readers before they are lost.
- A short, honest re-engagement sequence comes before suspending inactive contacts.
- A written, automated sunset policy keeps the list healthy without sudden purges.
